TEDS Data Dictionary

Variables in the 3 Year Dataset

The table on this page lists all 3 Year variables. This includes all item variables from the 3 Year booklets, as well as derived variables that are based on 3 Year items.

The table does not include background variables that originate from other sources (either from admin data or from other study datasets). Such variables include IDs, twin sex and zygosity variables, the random variable and general exclusion variables. See the background variables page for details.

Variables are listed in alphabetical order in the table below. The columns of the table are:

Dataset variable name
Dataset variable label (in SPSS)
Source of data:
- child - from the child booklet
- parent - from the parent booklet
Item or derived variable? - see item coding for the parent and child booklets (pdfs) for item variables; see also the description of derived variables for more information.
Data type:
- integer - numeric whole numbers
- decimal - numeric with fractional values
Variable type:
- nominal - categorical, with arbitrary numeric values
- ordinal - categorical, with ordered numeric values (test items used as scores are treated as being ordinal even if they have a simple 0/1 coding)
- quantitative - numerical measurements of some concrete quantity such as length or time
- scale value - numerical measurement derived (usually) as a sum or mean of other variables
Coding or range of values - this shows the value coding used for nominal/ordinal variables, or an approximate range of values for quantitative and scale variables.

dataset variable name	dataset variable label	source of data	item or derived variable?	data type	variable level	coding or approximate range of values
cac011/2	Active child item 1: playing house (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac021/2	Active child item 2: playing with girls (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac031/2	Active child item 3: pretends female character (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac041/2	Active child item 4: plays male job (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac051/2	Active child item 5: fighting (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac061/2	Active child item 6: pretends family character (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac071/2	Active child item 7: sports/ball games (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac081/2	Active child item 8: climbing (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac091/2	Active child item 9: playing at baby care (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac101/2	Active child item 10: interest in cars (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac111/2	Active child item 11: dressing in girlish clothes (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac121/2	Active child item 12: guns (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac131/2	Active child item 13: jewellery (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac141/2	Active child item 14: tool set (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac151/2	Active child item 15: dolls (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac161/2	Active child item 16: trains (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac171/2	Active child item 17: swords (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac181/2	Active child item 18: tea set (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac191/2	Active child item 19: explore new surroundings (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac201/2	Active child item 20: rough play (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac211/2	Active child item 21: interest in snakes (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac221/2	Active child item 22: avoids dirt (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac231/2	Active child item 23: likes pretty things (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cac241/2	Active child item 24: avoids risks (3 Year), see value labels	child	item	integer	ordinal	1=never, 2=hardly even, 3=sometimes, 4=often, 5=very often
cadparc1/2	Parent-administered Parca total score (3 Year), 0-1	child	derived	decimal	scale	0 to 1
cadparn1/2	Parent-administered Parca mean score (3 Year), standardised	child	derived	decimal	scale	approx. -3 to +3 (standardised)
cagemdex	Exclude on moderate twin age rules (3 Year), 1Y 0N	child	derived	integer	nominal	0=no, 1=yes
cagestex	Exclude on strict twin age rules (3 Year), 1Y 0N	child	derived	integer	nominal	0=no, 1=yes
calg2zy	Zygosity derived from questionnaire only (3 Year), see value labels	parent	derived	integer	nominal	1=MZ, 2=DZ, 5=indeterminate, 99=inconsistent data
calgzyg	Zygosity derived from questionnaire and twin sexes (3 Year), see value labels	parent	derived	integer	nominal	1=MZ, 2=DZ, 5=indeterminate, 99=inconsistent data
canx021/2	Behaviour item 45: slow to warm to strangers (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
canx071/2	Behaviour item 39: shy or timid (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
canx161/2	Behaviour item 30: upset when parent leaves (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
canx201/2	Behaviour item 6: resists sleeping alone (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
canx221/2	Behaviour item 34: afraid of everyday things (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
canxfeart1/2	ARBQ Fear subscale (3 Year), 0-4	child	derived	decimal	scale	0 to 4
canxshyt1/2	ARBQ Shyness (social anxiety) subscale (3 Year), 0-6	child	derived	decimal	scale	0 to 6
canxt1/2	ARBQ total scale (3 Year), 0-28	child	derived	decimal	scale	0 to 28
capalon1/2	Twins apart: respondent alone with twin (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
capbed	Twins apart: different bed times (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
capoth1/2	Twins apart: respondent alone with twin (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
capother	Twins apart: others alone with twin (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
captothh	Twins apart: number of hours per week (3 Year), see value labels	parent	item	integer	ordinal	1=1 hour, 2=2 hours, 3=3 hours, 4=4 hours, 5=5-6 hours, 6=7-10 hours, 8=over 10 hours
capwake	Twins apart: wake at different times (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cbedfrnd	How often twins are put to bed by friends (3 Year), see value labels	parent	item	integer	ordinal	3=often/daily, 2=frequently/weekly, 1=occasionally/monthly, 0=never
cbedopar	How often twins are put to bed by other parent (3 Year), see value labels	parent	item	integer	ordinal	3=often/daily, 2=frequently/weekly, 1=occasionally/monthly, 0=never
cbedorel	How often twins are put to bed by relatives (3 Year), see value labels	parent	item	integer	ordinal	3=often/daily, 2=frequently/weekly, 1=occasionally/monthly, 0=never
cbedoth	How often twins are put to bed by others (3 Year), see value labels	parent	item	integer	ordinal	3=often/daily, 2=frequently/weekly, 1=occasionally/monthly, 0=never
cbedprof	How often twins are put to bed by carers (3 Year), see value labels	parent	item	integer	ordinal	3=often/daily, 2=frequently/weekly, 1=occasionally/monthly, 0=never
cbedrmsh	Do twins share a room with anyone else (3 Year), see value labels	parent	item	integer	nominal	0=no, 1=yes with each other, 2=yes with each other and someone else, 3=yes with someone else
cbedsh1/2	Twin shares bed (3 Year), 1Y 0N	parent	derived	integer	nominal	0=no, 1=yes
cbeh011/2	Behaviour item 1: fair in games (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh021/2	Behaviour item 2: restless (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh031/2	Behaviour item 3: considerate (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh041/2	Behaviour item 4: fidgety (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh051/2	Behaviour item 5: destroys belongings (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh061/2	Behaviour item 7: affectionate to family (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh071/2	Behaviour item 9: fights other children (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh081/2	Behaviour item 10: not liked by other children (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh091/2	Behaviour item 11: volunteers help at home (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh101/2	Behaviour item 13: worried (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh111/2	Behaviour item 14: solitary (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh121/2	Behaviour item 15: irritable (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh131/2	Behaviour item 16: helps people if hurt (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh141/2	Behaviour item 17: miserable (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh151/2	Behaviour item 18: twitches or mannerisms (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh161/2	Behaviour item 19: bites nails/fingers (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh171/2	Behaviour item 20: disobedient (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh181/2	Behaviour item 21: kind to young children (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh191/2	Behaviour item 23: poor concentration (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh201/2	Behaviour item 24: afraid of new situations (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh211/2	Behaviour item 25: helps ill children (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh221/2	Behaviour item 26: fussy (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh231/2	Behaviour item 27: tells lies (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh241/2	Behaviour item 28: wets or soils self (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh251/2	Behaviour item 29: comforts upset children (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh261/2	Behaviour item 31: stutter or stammer (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh271/2	Behaviour item 32: other speech difficulty (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh281/2	Behaviour item 33: plays imaginatively (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh291/2	Behaviour item 35: bullies (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh301/2	Behaviour item 36: inattentive (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh311/2	Behaviour item 37: gets on with other children (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh31r1/2	Reversed version of behaviour item 37 (3 Year), see value labels	child	item	integer	ordinal	2=not true, 1=sometimes true, 0=certainly true
cbeh321/2	Behaviour item 40: does not share toys (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh331/2	Behaviour item 41: cries easily (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh341/2	Behaviour item 42: forceful/determined (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh351/2	Behaviour item 43: blames others (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh361/2	Behaviour item 44: shares treats (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh371/2	Behaviour item 46: gives up easily (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh381/2	Behaviour item 47: inconsiderate (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh391/2	Behaviour item 48: independent/confident (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh39r1/2	Reversed version of behaviour item 48 (3 Year), see value labels	child	item	integer	ordinal	2=not true, 1=sometimes true, 0=certainly true
cbeh401/2	Behaviour item 49: kicks/bites other children (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh411/2	Behaviour item 50: kind to animals (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh421/2	Behaviour item 51: stares blankly (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh431/2	Behaviour item 52: stops quarrels (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbeh441/2	Behaviour item 22: frequent stomachaches or sickness (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
cbmopreg	Is mother pregnant (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cbpamus	Being a parent item 3: amused, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=untrue, 2, 3, 4, 5=true
cbpamus1/2	Being a parent item 3: amused, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cbpamusd	Being a parent item 3: amused, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cbpangr	Being a parent item 5: angry, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=untrue, 2, 3, 4, 5=true
cbpangr1/2	Being a parent item 5: angry, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cbpangrd	Being a parent item 5: angry, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cbpaway	Being a parent item 4: wish away, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=untrue, 2, 3, 4, 5=true
cbpaway1/2	Being a parent item 4: wish away, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cbpawayd	Being a parent item 4: wish away, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cbpclos	Being a parent item 6: feel close, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=untrue, 2, 3, 4, 5=true
cbpclos1/2	Being a parent item 6: feel close, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cbpclosd	Being a parent item 6: feel close, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cbpfrus	Being a parent item 7: frustrated, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=untrue, 2, 3, 4, 5=true
cbpfrus1/2	Being a parent item 7: frustrated, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cbpfrusd	Being a parent item 7: frustrated, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cbphapp	Being a parent item 2: happy relationship, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=untrue, 2, 3, 4, 5=true
cbphapp1/2	Being a parent item 2: happy relationship, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cbphappd	Being a parent item 2: happy relationship, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cbpimpa	Being a parent item 1: impatient, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=untrue, 2, 3, 4, 5=true
cbpimpa1/2	Being a parent item 1: impatient, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cbpimpad	Being a parent item 1: impatient, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
ccbmi1/2	Twin BMI (3 Year), kilograms per square metre	child	derived	decimal	quantitative	approx. 10 to 30 (kilograms per square metre)
ccc011/2	Communication item 1: concerns about speech/language (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
ccc01a1/2	Communication item 1a: slow language development concerns (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
ccc01b1/2	Communication item 1b: intelligible speech concerns (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
ccc01c1/2	Communication item 1c: misunderstands others concerns (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
ccc01d1/2	Communication item 1d: pronunciation concerns (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
ccc01e1/2	Communication item 1e: poor hearing concerns (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
ccc01f1/2	Communication item 1f: stuttering concerns (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
ccc01g1/2	Communication item 1g: other concerns (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
ccc01s1/2	Communication item 1s: seen professional specialist about concerns (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
ccc021/2	Communication item 2: uses finger to show interest (3 Year), see value labels	child	item	integer	ordinal	1=often, 2=sometimes, 3=never
ccc031/2	Communication item 3: follows line of gaze (3 Year), see value labels	child	item	integer	ordinal	1=usually, 2=sometimes, 3=usually not
ccc041/2	Communication item 4: meaningless but fluent speech (3 Year), see value labels	child	item	integer	ordinal	1=often, 2=sometimes, 3=never
ccc051/2	Communication item 5: twins have their own language (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
ccc061/2	Communication item 6: echoes what people say (3 Year), see value labels	child	item	integer	ordinal	1=often, 2=sometimes, 3=never
ccc071/2	Communication item 7: recites rhymes or jingles (3 Year), see value labels	child	item	integer	nominal	0=no, 1=yes unusually often, 2=yes sometimes
ccc081/2	Communication item 8: language has gone into decline (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
ccd011/2	Diet item 1: finish dinner (3 Year), see value labels	child	item	integer	ordinal	1=disagree, 2=slightly disagree, 3=do not agree or disagree, 4=slightly agree, 5=agree
ccd021/2	Diet item 2: eat everything on plate (3 Year), see value labels	child	item	integer	ordinal	1=disagree, 2=slightly disagree, 3=do not agree or disagree, 4=slightly agree, 5=agree
ccd031/2	Diet item 3: eat only at mealtimes (3 Year), see value labels	child	item	integer	ordinal	1=disagree, 2=slightly disagree, 3=do not agree or disagree, 4=slightly agree, 5=agree
ccd041/2	Diet item 4: has to be encouraged (3 Year), see value labels	child	item	integer	ordinal	1=disagree, 2=slightly disagree, 3=do not agree or disagree, 4=slightly agree, 5=agree
ccd051/2	Diet item 5: told off for playing (3 Year), see value labels	child	item	integer	ordinal	1=disagree, 2=slightly disagree, 3=do not agree or disagree, 4=slightly agree, 5=agree
ccd061/2	Diet item 6: ensure eats enough (3 Year), see value labels	child	item	integer	ordinal	1=disagree, 2=slightly disagree, 3=do not agree or disagree, 4=slightly agree, 5=agree
ccd071/2	Diet item 7: OK to snack (3 Year), see value labels	child	item	integer	ordinal	1=disagree, 2=slightly disagree, 3=do not agree or disagree, 4=slightly agree, 5=agree
cchatot	Chaos overall scale (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cchtcm1/2	Child height (3 Year), centimetres	child	item	integer	quantitative	approx. 60 to 120 (centimetres)
ccomplx1/2	Sentence Complexity total score (3 Year), 0-12	child	derived	integer	scale	0 to 12
ccont1/2	Overall Behar Conduct problems scale (3 Year), 0-18	child	derived	decimal	scale	0 to 18
ccwtkg1/2	Child weight (3 Year), kilograms	child	item	decimal	quantitative	approx. 10 to 25 (kilograms)
cdiasko	Discipline item 6: ask someone else, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=never, 2, 3=sometimes, 4, 5=usually
cdiasko1/2	Discipline item 6: ask someone else, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cdiaskod	Discipline item 6: ask someone else, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cdiexpl	Discipline item 3: explain or reason, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=never, 2, 3=sometimes, 4, 5=usually
cdiexpl1/2	Discipline item 3: explain or reason, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cdiexpld	Discipline item 3: explain or reason, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cdifirm	Discipline item 4: firm and calm, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=never, 2, 3=sometimes, 4, 5=usually
cdifirm1/2	Discipline item 4: firm and calm, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cdifirmd	Discipline item 4: firm and calm, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cdijoke	Discipline item 5: make a joke, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=never, 2, 3=sometimes, 4, 5=usually
cdijoke1/2	Discipline item 5: make a joke, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cdijoked	Discipline item 5: make a joke, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cdis1/2	Discipline overall scale (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cdisavo1/2	Parental discipline avoidance scale, ask/joke (3 year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cdishou	Discipline item 2: shout/tell off, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=never, 2, 3=sometimes, 4, 5=usually
cdishou1/2	Discipline item 2: shout/tell off, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cdishoud	Discipline item 2: shout/tell off, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cdismak	Discipline item 1: smack or slap, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=never, 2, 3=sometimes, 4, 5=usually
cdismak1/2	Discipline item 1: smack or slap, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cdismakd	Discipline item 1: smack or slap, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cdisneg1/2	Parental discipline harsh/negative scale, smack/shout (3 year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cdispos1/2	Parental discipline positive scale, explain/firm (3 year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cdrawt1/2	Drawing test total score (3 Year), 0-9	child	derived	integer	scale	0 to 9
cdrcheap	Dress twins similarly: its cheaper (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cdrdiff	Tell twins apart by their dress (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cdreasy	Dress twins similarly: its easy (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cdress	Dress twins similarly (3 Year), see value labels	parent	item	integer	nominal	0=no never, 1=yes usually, 2=yes sometimes, 3=no but I coordinate their clothes
cdrgiven	Dress twins similarly: given matching clothes (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cdrilike	Dress twins similarly: like them to match (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cdrother	Dress twins similarly: other reason (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cdrpknow	Dress twins similarly: people know they are twins (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cdrtwlik	Dress twins similarly: they like it (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cemot1/2	Overall Behar Emotion problems scale (3 Year), 0-12	child	derived	decimal	scale	0 to 12
cerisk1/2	Twin Environment Risk composite (3 Year), standardised	child	derived	decimal	scale	approx. -3 to +3 (standardised)
ceriskf	Family Environment Risk composite (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cexcludm	General exclusion combined with moderate twin age rules (3 Year), 1Y 0N	child	derived	integer	nominal	0=no, 1=yes
cexcluds	General exclusion combined with strict twin age rules (3 Year), 1Y 0N	child	derived	integer	nominal	0=no, 1=yes
cfbmi	Father BMI (3 Year), kilograms per square metre	child	derived	decimal	quantitative	approx. 20 to 35 (kilograms per square metre)
cfbmcat1/2	Father BMI category (3 Year), see value labels	child	derived	integer	ordinal	1=underweight, 2=normal, 3=overweight, 4=obese
cfemale1/2	Female gender role scale (3 Year), 12-60	child	derived	decimal	scale	12 to 60
cfhtcm	Father height (3 Year), centimetres	child	item	integer	quantitative	approx. 160 to 200 (centimetres)
cfwtkg	Father weight (3 Year), kilograms	child	item	decimal	quantitative	approx. 60 to 120 (kilograms)
cgboard	Twin play item 8: board games, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=less than once monthly, 2=once or twice monthly, 3=once or twice weekly, 4=several times weekly, 5=almost daily
cgboard1/2	Twin play item 8: board games, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cgboardd	Twin play item 8: board games, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cgbooks	Twin play item 5: childrens books, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=none, 2=1-10, 3=11-50, 4=51-100, 5=101 or more
cgbooks1/2	Twin play item 5: childrens books, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cgbooksd	Twin play item 5: childrens books, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cgcoord	Twin play item 9: do twins have coordination toys (3 Year), see value labels	parent	item	integer	ordinal	1=always available, 2=usually put away, 3=no or not yet
cgdough	Twin play item 9: do twins have play dough/clay (3 Year), see value labels	parent	item	integer	ordinal	1=always available, 2=usually put away, 3=no or not yet
cgender1/2	Gender role total scale (3 Year), 0-100	child	derived	decimal	scale	0 to 100
cgfac11/2	Twin play scale 1: books/puzzles/tapes (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cgfac21/2	Twin play scale 2: games (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cggfac1z	Twin play per-family scale 2: indoor toys (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cggfac2z	Twin discipline scale 1: smack/shout (3 year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cgmessy	Twin play item 1: messy play, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=less than once monthly, 2=once or twice monthly, 3=once or twice weekly, 4=several times weekly, 5=almost daily
cgmessy1/2	Twin play item 1: messy play, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cgmessyd	Twin play item 1: messy play, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cgmobile	Twin play item 9: do twins have hanging mobile (3 Year), see value labels	parent	item	integer	ordinal	1=always available, 2=usually put away, 3=no or not yet
cgmusi	Twin play item 3: music player, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=less than once monthly, 2=once or twice monthly, 3=once or twice weekly, 4=several times weekly, 5=almost daily
cgmusi1/2	Twin play item 3: music player, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cgmusic	Twin play item 3: do twins have music player (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cgmusid	Twin play item 3: music player, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cgoutdor	Twin play item 9: do twins have outdoor toys (3 Year), see value labels	parent	item	integer	ordinal	1=always available, 2=usually put away, 3=no or not yet
cgphys	Twin play item 7: physical games, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=less than once monthly, 2=once or twice monthly, 3=once or twice weekly, 4=several times weekly, 5=almost daily
cgphys1/2	Twin play item 7: physical games, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cgphysd	Twin play item 7: physical games, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cgpsamec	Twins are in the same class at play group (3 Year), see value labels	parent	item	integer	ordinal	0=no, 1=yes sometimes, 2=yes always
cgpsamen	Twins attend the same play group (3 Year), see value labels	parent	item	integer	ordinal	0=no, 1=yes sometimes, 2=yes always
cgpuzz	Twin play item 2: puzzles, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=none, 2=1-3, 3=4-6, 4=7-10, 5=11 or more
cgpuzz1/2	Twin play item 2: puzzles, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cgpuzzd	Twin play item 2: puzzles, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cgramma1/2	Grammar composite score (3 Year), 0-4	child	derived	integer	scale	0 to 4
cgtapes	Twin play item 4: childrens recordings, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=none, 2=1-3, 3=4-6, 4=7-10, 5=11 or more
cgtapes1/2	Twin play item 4: childrens recordings, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cgtapesd	Twin play item 4: childrens recordings, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cgtricyc	Twin play item 9: do twins have tricycles/scooters (3 Year), see value labels	parent	item	integer	ordinal	1=always available, 2=usually put away, 3=no or not yet
cgzoo	Twin play item 6: taken to zoo, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=no, 2=once, 3=2-3 times, 4=4-5 times, 5=6 or more times
cgzoo1/2	Twin play item 6: taken to zoo, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cgzood	Twin play item 6: taken to zoo, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
chache1/2	Twin hearing problem: earache (3 Year), see value labels	parent	item	integer	ordinal	3=often, 2=sometimes, 1=occasionally, 0=never
chand1/2	Twin handedness: less stringent classification (3 Year), see value labels	child	derived	integer	nominal	1=left handed, 2=right handed, 3=mixed handedness
chands1/2	Twin handedness: more stringent classification (3 Year), see value labels	child	derived	integer	nominal	1=left handed, 2=right handed, 3=mixed handedness
chcatar1/2	Twin hearing problem: catarrh during cold (3 Year), see value labels	parent	item	integer	ordinal	3=often, 2=sometimes, 1=occasionally, 0=never
chignor1/2	Twin hearing problem: ignore what people saying (3 Year), see value labels	parent	item	integer	ordinal	3=often, 2=sometimes, 1=occasionally, 0=never
chmouth1/2	Twin hearing problem: mouth breathing (3 Year), see value labels	parent	item	integer	ordinal	3=often, 2=sometimes, 1=occasionally, 0=never
chosp1/2	Health item 13: admitted to hospital in last year (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
chospca1/2	Health item 14: hospital casualty in last year (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
chospcx1/2	Health item 14: number of times to hospital casualty in last year (3 Year), see value labels	child	item	integer	ordinal	1=1, 2=2, 3=3 or more times
chospdd1/2	Health item 13: longest stay in hospital in last year (3 Year), see value labels	child	item	integer	ordinal	1=1, 2=2, 3=3-4, 4=5 or more days
chospfa	Father needed hospital (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
chospmo	Mother needed hospital (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
chospsib	Sibling needed hospital (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
chospx1/2	Health item 13: number of times admitted to hospital (3 Year), see value labels	child	item	integer	ordinal	1=1, 2=2, 3=3 or more times
chpus1/2	Twin hearing problem: pus in ears (3 Year), see value labels	parent	item	integer	ordinal	3=often, 2=sometimes, 1=occasionally, 0=never
chsnore1/2	Twin hearing problem: snore (3 Year), see value labels	parent	item	integer	ordinal	3=often, 2=sometimes, 1=occasionally, 0=never
chsusp1/2	Twin hearing problem: ever suspected (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
chtalk1/2	Twin hearing problem: talking problem (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
chyp11/2	Behaviour item 8: difficulty completing activities (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
chyp21/2	Behaviour item 38: difficulty waiting (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
chyp31/2	Behaviour item 12: touches things not allowed (3 Year), see value labels	child	item	integer	ordinal	0=not true, 1=sometimes true, 2=certainly true
chypt1/2	Overall (Behar + Hyperactivity) Hyperactivity scale (3 Year), 0-16	child	derived	decimal	scale	0 to 16
cillfa	Father seriously ill (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cillfam	Serious illness in the family (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cillmo	Mother seriously ill (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cillsib	Sibling seriously ill (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cjobch	Has respondent job changed (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cjobchp	Has partner job changed (3 Year), see value labels	parent	item	integer	nominal	0=no, 1=yes, 2=do not have a partner
cld1/2	Health item 11: learning disability (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cleft1/2	Twin is left handed: less stringent criteria (3 Year), 1Y 0N	child	derived	integer	nominal	0=no, 1=yes
clifeev	Life events composite: count of events (3 Year), 0-5	parent	derived	integer	scale	0 to 5
clilamp1/2	Twin goes to sleep with: lamp in room (3 Year), 1Y 0N	parent	derived	integer	nominal	0=no, 1=yes
cliland1/2	Twin goes to sleep with: landing light (3 Year), 1Y 0N	parent	derived	integer	nominal	0=no, 1=yes
clinigt1/2	Twin goes to sleep with: night light (3 Year), 1Y 0N	parent	derived	integer	nominal	0=no, 1=yes
clinone1/2	Twin goes to sleep with: no light (3 Year), 1Y 0N	parent	derived	integer	nominal	0=no, 1=yes
cliroom1/2	Twin goes to sleep with: room light (3 Year), 1Y 0N	parent	derived	integer	nominal	0=no, 1=yes
cmale1/2	Male gender role scale (3 Year), 12-60	child	derived	decimal	scale	12 to 60
cmatcht1/2	Matching test total score (3 Year), 0-14	child	derived	integer	scale	0 to 14
cmbmi	Mother BMI (3 Year), kilograms per square metre	child	derived	decimal	quantitative	approx. 17 to 40 (kilograms per square metre)
cmbmcat1/2	Mother BMI category (3 Year), see value labels	child	derived	integer	ordinal	1=underweight, 2=normal, 3=overweight, 4=obese
cmdanx	Maternal depression item 4: anxious or worried (3 Year), see value labels	parent	item	integer	ordinal	0=no never/not at all, 1=not very much, 2=yes sometimes/quite often, 3=yes often/most of the time
cmdblame	Maternal depression item 3: blamed myself (3 Year), see value labels	parent	item	integer	ordinal	0=no never/not at all, 1=not very much, 2=yes sometimes/quite often, 3=yes often/most of the time
cmdcry	Maternal depression item 9: crying (3 Year), see value labels	parent	item	integer	ordinal	0=no never/not at all, 1=not very much, 2=yes sometimes/quite often, 3=yes often/most of the time
cmdenjoy	Maternal depression item 2: enjoy looking forward (3 Year), see value labels	parent	item	integer	ordinal	0=as much as ever, 1=rather less than before, 2=definitely not so much now, 3=hardly/not at all
cmdharm	Maternal depression item 10: thoughts of self harm (3 Year), see value labels	parent	item	integer	ordinal	0=no never/not at all, 1=not very much, 2=yes sometimes/quite often, 3=yes often/most of the time
cmdlaugh	Maternal depression item 1: laugh/see funny side (3 Year), see value labels	parent	item	integer	ordinal	0=as much as ever, 1=rather less than before, 2=definitely not so much now, 3=hardly/not at all
cmdontop	Maternal depression item 6: getting on top of me (3 Year), see value labels	parent	item	integer	ordinal	0=no never/not at all, 1=not very much, 2=yes sometimes/quite often, 3=yes often/most of the time
cmdsad	Maternal depression item 8: sad or miserable (3 Year), see value labels	parent	item	integer	ordinal	0=no never/not at all, 1=not very much, 2=yes sometimes/quite often, 3=yes often/most of the time
cmdscare	Maternal depression item 5: scared or panicky (3 Year), see value labels	parent	item	integer	ordinal	0=no never/not at all, 1=not very much, 2=yes sometimes/quite often, 3=yes often/most of the time
cmdtot	Maternal depression scale (3 Year), 0-30	parent	derived	decimal	scale	0 to 30
cmdunhap	Maternal depression item 7: unhappy, difficult sleeping (3 Year), see value labels	parent	item	integer	ordinal	0=no never/not at all, 1=not very much, 2=yes sometimes/quite often, 3=yes often/most of the time
cmhtcm	Mother height (3 Year), centimetres	child	item	integer	quantitative	approx. 140 to 190 (centimetres)
cmilk1/2	Twin fed breast milk and to what age (3 Year), see value labels	parent	derived	integer	ordinal	0=never breast fed, 1=1 week or less, 2=2 weeks, 3=3-4 weeks, 4=2-3 months, 5=4-6 months, 6=7-12 months, 7=over 12 months, 8=still breast fed
cmstatus	Respondent marital status (3 Year), see value labels	parent	item	integer	nominal	1=married to parent of twins, 2=married to other, 3=cohabiting with parent of twins, 4=cohabiting with other, 5=divorced, 6=separated, 7=widowed, 8=unmarried
cmwtkg	Mother weight (3 Year), kilograms	child	item	decimal	quantitative	approx. 40 to 120 (kilograms)
codd011/2	Odd One Out item 1 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd01s1/2	Odd One Out item 1 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd021/2	Odd One Out item 2 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd02s1/2	Odd One Out item 2 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd031/2	Odd One Out item 3 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd03s1/2	Odd One Out item 3 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd041/2	Odd One Out item 4 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd04s1/2	Odd One Out item 4 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd051/2	Odd One Out item 5 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd05s1/2	Odd One Out item 5 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd061/2	Odd One Out item 6 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd06s1/2	Odd One Out item 6 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd071/2	Odd One Out item 7 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd07s1/2	Odd One Out item 7 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd081/2	Odd One Out item 8 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd08s1/2	Odd One Out item 8 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd091/2	Odd One Out item 9 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd09s1/2	Odd One Out item 9 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd101/2	Odd One Out item 10 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd10s1/2	Odd One Out item 10 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd111/2	Odd One Out item 11 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd11s1/2	Odd One Out item 11 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd121/2	Odd One Out item 12 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd12s1/2	Odd One Out item 12 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd131/2	Odd One Out item 13 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd13s1/2	Odd One Out item 13 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd141/2	Odd One Out item 14 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd14s1/2	Odd One Out item 14 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd151/2	Odd One Out item 15 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd15s1/2	Odd One Out item 15 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
codd161/2	Odd One Out item 16 response (3 Year), see value labels	child	item	integer	nominal	1/2/3=picture selected, 5=invalid selection
codd16s1/2	Odd One Out item 16 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
coddre11/2	Odd One Out feedback item 1: cannot do/do not like (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
coddre21/2	Odd One Out feedback item 2: angry/frustrated (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
coddre31/2	Odd One Out feedback item 3: shrug/turn away (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
coddre41/2	Odd One Out feedback item 4: wanted to stop (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
coddt1/2	Odd one out test total score (3 Year), 0-14	child	derived	integer	scale	0 to 14
cpar1/2	Being a parent overall feelings scale (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cparca1/2	Parca overall mean score (3 Year), standardised	child	derived	decimal	scale	approx. -3 to +3 (standardised)
cparent	Parent booklet data present (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cparneg1/2	Being a parent twin scale 1: negative feelings (3 year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cparpos1/2	Being a parent twin scale 2: positive feelings (3 year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cpbage	Twin age in years on completion of parent booklet (3 Year)	parent	derived	decimal	quantitative	approx. 2.8 to 3.6 (years)
cpbLLCage	Age of twin when 3 year parent booklet completed (for use in LLC TRE), months	parent	derived	integer	quantitative	approx. 34 to 45 (months)
cpbLLCdate	Date when 3 year parent booklet completed (for use in LLC TRE), yyyy-mm string	parent	derived	string	date value	approx. '1996-12' to '1999-03'
cpd011/2	Drawing item 1 score (3 Year), 0 or 1	child	item	integer	ordinal	0, 1 (scores)
cpd021/2	Drawing item 2 score (3 Year), 0 or 1	child	item	integer	ordinal	0, 1 (scores)
cpd031/2	Drawing item 3 score (3 Year), 0 or 1	child	item	integer	ordinal	0, 1 (scores)
cpd041/2	Drawing item 4 score (3 Year), 0 or 1 or 2	child	item	integer	ordinal	0, 1, 2 (scores)
cpd04h1/2	Drawing item 4 hand used (3 Year), see value labels	child	item	integer	nominal	1=left, 2=right, 3=both
cpd051/2	Drawing item 5 score (3 Year), 0 or 1 or 2	child	item	integer	ordinal	0, 1, 2 (scores)
cpd05h1/2	Drawing item 5 hand used (3 Year), see value labels	child	item	integer	nominal	1=left, 2=right, 3=both
cpd061/2	Drawing item 6 score (3 Year), 0 or 1 or 2	child	item	integer	ordinal	0, 1, 2 (scores)
cpd06h1/2	Drawing item 6 hand used (3 Year), see value labels	child	item	integer	nominal	1=left, 2=right, 3=both
cpdrep11/2	Drawing feedback item 1: cannot do/do not like (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cpdrep21/2	Drawing feedback item 2: angry/frustrated (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cpdrep31/2	Drawing feedback item 3: shrug/turn away (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cpdrep41/2	Drawing feedback item 4: wanted to stop (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cpdrink1/2	Twin potty training: no drink before bed (3 Year), see value labels	parent	item	integer	ordinal	2=often, 1=sometimes, 0=never
cpdryda1/2	Twin dry throughout day (3 Year), see value labels	parent	item	integer	ordinal	4=always, 3=mostly, 2=sometimes, 1=hardly ever, 0=never
cpdryexp	Age when you expect twins to be dry at night (3 Year), see value labels	parent	item	integer	ordinal	1=2yrs, 2=2.5yrs, 3=3yrs, 4=3.5yrs, 5=4yrs, 6=4.5yrs, 7=5yrs or older
cpdrynt1/2	Twin dry throughout night (3 Year), see value labels	parent	item	integer	ordinal	4=always, 3=mostly, 2=sometimes, 1=hardly ever, 0=never
cplaygp1/2	Twin attends play group (3 Year), 1Y 0N	parent	derived	integer	nominal	0=no, 1=yes
cplift1/2	Twin potty training: lift without waking (3 Year), see value labels	parent	item	integer	ordinal	2=often, 1=sometimes, 0=never
cpm011/2	Matching item 1 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm01s1/2	Matching item 1 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm021/2	Matching item 2 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm02s1/2	Matching item 2 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm031/2	Matching item 3 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm03s1/2	Matching item 3 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm041/2	Matching item 4 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm04s1/2	Matching item 4 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm051/2	Matching item 5 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm05s1/2	Matching item 5 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm061/2	Matching item 6 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm06s1/2	Matching item 6 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm071/2	Matching item 7 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm07s1/2	Matching item 7 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm081/2	Matching item 8 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm08s1/2	Matching item 8 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm091/2	Matching item 9 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm09s1/2	Matching item 9 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm101/2	Matching item 10 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm10s1/2	Matching item 10 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm111/2	Matching item 11 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm11s1/2	Matching item 11 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm121/2	Matching item 12 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm12s1/2	Matching item 12 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm131/2	Matching item 13 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm13s1/2	Matching item 13 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm141/2	Matching item 14 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm14s1/2	Matching item 14 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm151/2	Matching item 15 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm15s1/2	Matching item 15 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpm161/2	Matching item 16 response (3 Year), see value labels	child	item	integer	nominal	1/2/3/4=picture selected, 5=invalid selection
cpm16s1/2	Matching item 16 correct score (3 Year), 1Y 0N	child	derived	integer	ordinal	0=no, 1=yes
cpmrep11/2	Matching feedback item 1: cannot do/do not like (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cpmrep21/2	Matching feedback item 2: angry/frustrated (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cpmrep31/2	Matching feedback item 3: shrug/turn away (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cpmrep41/2	Matching feedback item 4: wanted to stop (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cpnapda1/2	Twin still wears nappies during day (3 Year), see value labels	parent	item	integer	ordinal	2=always, 1=sometimes, 0=never
cpnapnt1/2	Twin still wears nappies at night (3 Year), see value labels	parent	item	integer	ordinal	2=always, 1=sometimes, 0=never
cpnapp1/2	Twin potty training: try without nappies (3 Year), see value labels	parent	item	integer	ordinal	2=often, 1=sometimes, 0=never
cpottrn1/2	Trying potty training twin now (3 Year), 1Y 0N	parent	derived	integer	nominal	0=no, 1=yes
cpottrp1/2	Tried potty training twin in past (3 Year), 1Y 0N	parent	derived	integer	nominal	0=no, 1=yes
cpotty1/2	Twin knows when to use toilet/potty during day (3 Year), see value labels	parent	item	integer	ordinal	3=often, 2=sometimes, 1=occasionally, 0=never
cpparbd1/2	Twin potty training: sleep in parent bed (3 Year), see value labels	parent	item	integer	ordinal	2=often, 1=sometimes, 0=never
cpr011/2	Parent-report Parca item 1: jigsaw (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr021/2	Parent-report Parca item 2: jigsaw with 10+ pieces (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr031/2	Parent-report Parca item 3: build with bricks (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr041/2	Parent-report Parca item 4: beads/bricks in patterns (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr051/2	Parent-report Parca item 5: tell the time (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr061/2	Parent-report Parca item 6: draw straight line (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr071/2	Parent-report Parca item 7: draw recognisable pictures (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr081/2	Parent-report Parca item 8: draw a man with features (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr091/2	Parent-report Parca item 9: pretends with objects (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr101/2	Parent-report Parca item 10: pretends toys play together (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr111/2	Parent-report Parca item 11: pretend games with other children (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr121/2	Parent-report Parca item 12: games taking turns (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr131/2	Parent-report Parca item 13: trouble waiting turn (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr141/2	Parent-report Parca item 14: shows things are missing (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr151/2	Parent-report Parca item 15: put aside snacks for later (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr161/2	Parent-report Parca item 16: gather toys before playing (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr171/2	Parent-report Parca item 17: put things in piles without help (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr181/2	Parent-report Parca item 18: sorts coloured objects without help (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr191/2	Parent-report Parca item 19: fair when sharing snacks (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr201/2	Parent-report Parca item 20: changes games while playing (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr211/2	Parent-report Parca item 21: can group six objects (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr221/2	Parent-report Parca item 22: can do simple sums (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr231/2	Parent-report Parca item 23: avoids common dangers (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpr241/2	Parent-report Parca item 24: recognises reflection (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cpreass1/2	Twin potty training: reassure if wet (3 Year), see value labels	parent	item	integer	ordinal	2=often, 1=sometimes, 0=never
cproast1/2	Health item 2: problems with asthma (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cprocou1/2	Health item 1: problems with coughs (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cprodia1/2	Health item 9: problems with diabetes (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cproeye1/2	Health item 4: problems with eyesight (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cprofit1/2	Health item 3: problems with fits (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cprohd1/2	Health item 8: problems with headaches (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cproski1/2	Health item 5: problems with skin (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cprosto1/2	Health item 6: problems with stomachaches (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cprot1/2	Overall Behar Prosocial scale (3 Year), 0-20	child	derived	decimal	scale	0 to 20
cprovom1/2	Health item 7: problems with vomiting (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cprowk1/2	Health item 10: problems with weakness/paralysis (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cprward1/2	Twin potty training: offer rewards (3 Year), see value labels	parent	item	integer	ordinal	2=often, 1=sometimes, 0=never
cpwake1/2	Twin potty training: wake during night (3 Year), see value labels	parent	item	integer	ordinal	2=often, 1=sometimes, 0=never
crawg1/2	G: overall cognitive ability composite (3 Year), standardised	child	derived	decimal	scale	approx. -3 to +3 (standardised)
creparc1/2	Parent-reported Parca total score (3 Year), 0-22	child	derived	integer	scale	0 to 22
cright1/2	Twin is right handed: less stringent criteria (3 Year), 1Y 0N	child	derived	integer	nominal	0=no, 1=yes
cs00s1/2	Sentence complexity item 0: begun to combine words yet (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cs01s1/2	Sentence complexity item 1: picked me up (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cs02s1/2	Sentence complexity item 2: thats my truck (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cs03s1/2	Sentence complexity item 3: that coffee hot (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cs04s1/2	Sentence complexity item 4: like to read (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cs05s1/2	Sentence complexity item 5: dont want you (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cs06s1/2	Sentence complexity item 6: why did he (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cs07s1/2	Sentence complexity item 7: know who did it (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cs08s1/2	Sentence complexity item 8: think we got to go (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cs09s1/2	Sentence complexity item 9: want truck like he has (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cs10s1/2	Sentence complexity item 10: this big and this little (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cs11s1/2	Sentence complexity item 11: pig have a leg but cat dont (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cs12s1/2	Sentence complexity item 12: got broken by the car (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cscnv1/2	Non-verbal cognitive ability composite (3 Year), standardised	child	derived	decimal	scale	approx. -3 to +3 (standardised)
cscv1/2	Verbal cognitive ability composite (3 Year), standardised	child	derived	decimal	scale	approx. -3 to +3 (standardised)
csdqcbeht1/2	Total behaviour problems: SDQ-comparable Behar subscale (3 Year), 0-26	child	derived	decimal	scale	0 to 26
csdqccont1/2	Conduct problems: SDQ-comparable Behar subscale (3 Year), 0-8	child	derived	decimal	scale	0 to 8
csdqcemot1/2	Emotion problems: SDQ-comparable Behar subscale (3 Year), 0-6	child	derived	decimal	scale	0 to 6
csdqchypt1/2	Hyperactivity: SDQ-comparable Behar subscale (3 Year), 0-6	child	derived	decimal	scale	0 to 6
csdqcpert1/2	Peer probems: SDQ-comparable Behar subscale (3 Year), 0-6	child	derived	decimal	scale	0 to 6
csdqcprot1/2	Prosocial: SDQ-comparable Behar subscale (3 Year), 0-10	child	derived	decimal	scale	0 to 10
cseengp1/2	Health item 12: seen GP in last year (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
cseengx1/2	Health item 12: number of times seen GP in last year (3 Year), see value labels	child	item	integer	ordinal	1=1, 2=2, 3=3, 4=4, 5=5-6, 6=7-10, 7=11 or more times
csibnew	New siblings living at home (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
cslearl1/2	Twin sleep problem: waking early (3 Year), 1Y 0N	parent	derived	integer	nominal	0=no, 1=yes
cslnmar1/2	Twin sleep problem: nightmares (3 Year), 1Y 0N	parent	derived	integer	nominal	0=no, 1=yes
cslprob1/2	Twin sleep problem: difficulty getting to sleep (3 Year), 1Y 0N	parent	derived	integer	nominal	0=no, 1=yes
cslwake1/2	Twin sleep problem: frequent waking (3 Year), 1Y 0N	parent	derived	integer	nominal	0=no, 1=yes
csurage1/2	Health item 15: age on first operation in last year (3 Year), see value labels	child	item	integer	ordinal	1=2 years and 0-3 months, 2=2 years and 4-6 months, 3=2 years and 7-9 months, 4=2 years 10 months to 3 years
csurgga1/2	Health item 15: operation needed general anaesthetic (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
csurggx1/2	Health item 15: number of operations with general anaesthetic in last year (3 Year), see value labels	child	item	integer	ordinal	0=none, 1=1, 2=2 or more
csurgry1/2	Health item 15: surgical operation in last year (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
ctbook	Talking to twins item 6: read books, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=less than once monthly, 2=once or twice monthly, 3=once or twice weekly, 4=several times weekly, 5=almost daily
ctbook1/2	Talking to twins item 6: read books, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
ctbookd	Talking to twins item 6: read books, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cteat	Talking to twins item 8: choose what to eat, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=less than once monthly, 2=once or twice monthly, 3=once or twice weekly, 4=several times weekly, 5=almost daily
cteat1/2	Talking to twins item 8: choose what to eat, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cteatd	Talking to twins item 8: choose what to eat, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
ctempzyg	Zygosity difference scale (3 Year), 0-1	parent	derived	decimal	scale	approx. 0.3 to 1
ctfac11/2	Talking to twin scale 1: pronunciation/sentences/words (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
ctfac21/2	Talking to twin scale 2: rhymes/books/locations/talk (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cthreeyr	3 Year data present, 1Y 0N	parent, child	derived	integer	nominal	0=no, 1=yes
ctloca	Talking to twins item 5: directions/locations, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=less than once monthly, 2=once or twice monthly, 3=once or twice weekly, 4=several times weekly, 5=almost daily
ctloca1/2	Talking to twins item 5: directions/locations, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
ctlocad	Talking to twins item 5: directions/locations, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
ctoleft1/2	Twin is left handed: more stringent criteria (3 Year), 1Y 0N	child	derived	integer	nominal	0=no, 1=yes
ctorigh1/2	Twin is right handed: more stringent criteria (3 Year), 1Y 0N	child	derived	integer	nominal	0=no, 1=yes
ctpron	Talking to twins item 2: correct mispronunciation, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=never or rarely, 2=occasionally, 3=about half the time, 4=quite often, 5=almost always
ctpron1/2	Talking to twins item 2: correct mispronunciation, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
ctprond	Talking to twins item 2: correct mispronunciation, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
ctrhym	Talking to twins item 1: rhymes/songs/prayers, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=less than once monthly, 2=once or twice monthly, 3=once or twice weekly, 4=several times weekly, 5=almost daily
ctrhym1/2	Talking to twins item 1: rhymes/songs/prayers, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
ctrhymd	Talking to twins item 1: rhymes/songs/prayers, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
ctsent	Talking to twins item 3: correct sentences, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=never or rarely, 2=occasionally, 3=about half the time, 4=quite often, 5=almost always
ctsent1/2	Talking to twins item 3: correct sentences, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
ctsentd	Talking to twins item 3: correct sentences, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cttalk	Talking to twins item 7: talk around house, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=less than once monthly, 2=once or twice monthly, 3=once or twice weekly, 4=several times weekly, 5=almost daily
cttalk1/2	Talking to twins item 7: talk around house, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cttalkd	Talking to twins item 7: talk around house, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
ctvoc1/2	Transformed vocabulary total score (3 Year), 0-100	child	derived	decimal	scale	0 to 100
ctwdata1/2	Twin booklet data present (3 Year), 1Y 0N	child	item	integer	nominal	0=no, 1=yes
ctwbage1/2	Twin age in years on completion of twin booklet (3 Year)	child	derived	decimal	quantitative	approx. 2.8 to 3.6 (years)
ctwbagediff	Difference in twin ages on completion of twin booklet (3 Year), years	child	derived	decimal	quantitative	approx. 0 to 0.4 (years)
ctwbLLCage1	Age of twin when 3 year twin booklet completed (for use in LLC TRE), months	child	derived	integer	quantitative	approx. 35 to 43 (months)
ctwbLLCdate1	Date when 3 year twin booklet completed (for use in LLC TRE), yyyy-mm string	child	derived	string	date value	approx. '1996-12' to '1999-03'
ctword	Talking to twins item 4: correct wrong word, elder twin frequency (3 Year), see value labels	parent	item	integer	ordinal	1=never or rarely, 2=occasionally, 3=about half the time, 4=quite often, 5=almost always
ctword1/2	Talking to twins item 4: correct wrong word, twin-specific (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
ctwordd	Talking to twins item 4: correct wrong word, younger twin difference (3 Year), see value labels	parent	item	integer	ordinal	1=lot more, 2=little more, 3=about equally, 4=little less, 5=lot less
cuse1/2	Word use total score (3 Year), 0-12	child	derived	integer	scale	0 to 12
cvc0001/2	Vocabulary item 0: not talking yet (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0011/2	Vocabulary item 1: can say dinosaur (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0021/2	Vocabulary item 2: can say glass (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0031/2	Vocabulary item 3: can say catch (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0041/2	Vocabulary item 4: can say peculiar (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0051/2	Vocabulary item 5: can say donkey (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0061/2	Vocabulary item 6: can say jar (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0071/2	Vocabulary item 7: can say drop (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0081/2	Vocabulary item 8: can say before (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0091/2	Vocabulary item 9: can say reindeer (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0101/2	Vocabulary item 10: can say ladder (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0111/2	Vocabulary item 11: can say fasten (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0121/2	Vocabulary item 12: can say then (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0131/2	Vocabulary item 13: can say castle (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0141/2	Vocabulary item 14: can say material (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0151/2	Vocabulary item 15: can say forget/forgot (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0161/2	Vocabulary item 16: can say today (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0171/2	Vocabulary item 17: can say drum (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0181/2	Vocabulary item 18: can say stamp (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0191/2	Vocabulary item 19: can say hate (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0201/2	Vocabulary item 20: can say week (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0211/2	Vocabulary item 21: can say football (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0221/2	Vocabulary item 22: can say tyre (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0231/2	Vocabulary item 23: can say hurry (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0241/2	Vocabulary item 24: can say yesterday (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0251/2	Vocabulary item 25: can say microscope (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0261/2	Vocabulary item 26: can say furniture (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0271/2	Vocabulary item 27: can say leave (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0281/2	Vocabulary item 28: can say their (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0291/2	Vocabulary item 29: can say tricycle (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0301/2	Vocabulary item 30: can say kitchen (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0311/2	Vocabulary item 31: can say measure (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0321/2	Vocabulary item 32: can say they (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0331/2	Vocabulary item 33: can say kite (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0341/2	Vocabulary item 34: can say settee/sofa (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0351/2	Vocabulary item 35: can say peel (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0361/2	Vocabulary item 36: can say those (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0371/2	Vocabulary item 37: can say trolley (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0381/2	Vocabulary item 38: can say cloud (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0391/2	Vocabulary item 39: can say promise (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0401/2	Vocabulary item 40: can say yourself (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0411/2	Vocabulary item 41: can say lemon (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0421/2	Vocabulary item 42: can say fence (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0431/2	Vocabulary item 43: can say skate (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0441/2	Vocabulary item 44: can say why (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0451/2	Vocabulary item 45: can say peanut (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0461/2	Vocabulary item 46: can say hose (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0471/2	Vocabulary item 47: can say sneeze (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0481/2	Vocabulary item 48: can say about (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0491/2	Vocabulary item 49: can say cream cracker (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0501/2	Vocabulary item 50: can say pavement (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0511/2	Vocabulary item 51: can say somersault (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0521/2	Vocabulary item 52: can say above (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0531/2	Vocabulary item 53: can say salt (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0541/2	Vocabulary item 54: can say zoo (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0551/2	Vocabulary item 55: can say think (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0561/2	Vocabulary item 56: can say away (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0571/2	Vocabulary item 57: can say sauce (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0581/2	Vocabulary item 58: can say child (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0591/2	Vocabulary item 59: can say black (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0601/2	Vocabulary item 60: can say between (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0611/2	Vocabulary item 61: can say vanilla (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0621/2	Vocabulary item 62: can say cowboy (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0631/2	Vocabulary item 63: can say bored (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0641/2	Vocabulary item 64: can say on top of (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0651/2	Vocabulary item 65: can say vegetable (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0661/2	Vocabulary item 66: can say family (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0671/2	Vocabulary item 67: can say deep (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0681/2	Vocabulary item 68: can say each (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0691/2	Vocabulary item 69: can say beads (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0701/2	Vocabulary item 70: can say farmer (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0711/2	Vocabulary item 71: can say different (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0721/2	Vocabulary item 72: can say every (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0731/2	Vocabulary item 73: can say jeans (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0741/2	Vocabulary item 74: can say nobody (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0751/2	Vocabulary item 75: can say empty (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0761/2	Vocabulary item 76: can say none (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0771/2	Vocabulary item 77: can say elbow (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0781/2	Vocabulary item 78: can say nurse (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0791/2	Vocabulary item 79: can say expensive (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0801/2	Vocabulary item 80: can say might (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0811/2	Vocabulary item 81: can say nail (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0821/2	Vocabulary item 82: can say accident (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0831/2	Vocabulary item 83: can say fine (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0841/2	Vocabulary item 84: can say need to (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0851/2	Vocabulary item 85: can say thumb (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0861/2	Vocabulary item 86: can say circle (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0871/2	Vocabulary item 87: can say half (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0881/2	Vocabulary item 88: can say were (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0891/2	Vocabulary item 89: can say plaster/bandage (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0901/2	Vocabulary item 90: can say front (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0911/2	Vocabulary item 91: can say long (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0921/2	Vocabulary item 92: can say because (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0931/2	Vocabulary item 93: can say blade (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0941/2	Vocabulary item 94: can say idea (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0951/2	Vocabulary item 95: can say lost (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0961/2	Vocabulary item 96: can say because (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0971/2	Vocabulary item 97: can say computer (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0981/2	Vocabulary item 98: can say camping (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc0991/2	Vocabulary item 99: can say angry (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvc1001/2	Vocabulary item 100: can say however (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cvocab1/2	Vocabulary total score (3 Year), 0-100	child	derived	integer	scale	0 to 100
cwu011/2	Word use item 1: meaning of one (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cwu021/2	Word use item 2: ask what/where questions (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cwu031/2	Word use item 3: ask why/how questions (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cwu041/2	Word use item 4: reasons with because (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cwu051/2	Word use item 5: knows horse is an animal (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cwu061/2	Word use item 6: name shapes (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cwu071/2	Word use item 7: makes could/might statements (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cwu081/2	Word use item 8: asks meanings of words (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cwu091/2	Word use item 9: compares sizes of absent objects (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cwu101/2	Word use item 10: knows right and left (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cwu111/2	Word use item 11: words like biggest (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cwu121/2	Word use item 12: answers conditional questions (3 Year), 1Y 0N	child	item	integer	ordinal	0=no, 1=yes
cyhbed	Home chaos item 1: regular bedtime (3 Year), see value labels	parent	item	integer	ordinal	1=untrue, 2, 3, 4, 5=true
cyhcalm	Home chaos item 6: calm atmosphere (3 Year), see value labels	parent	item	integer	ordinal	1=untrue, 2, 3, 4, 5=true
cyhfac1z	Home chaos per-family scale 1: chaotic (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cyhfac2z	Home chaos per-family scale 2: calm (3 Year), standardised	parent	derived	decimal	scale	approx. -3 to +3 (standardised)
cyhhear	Home chaos item 2: cannot hear yourself think (3 Year), see value labels	parent	item	integer	ordinal	1=untrue, 2, 3, 4, 5=true
cyhontop	Home chaos item 4: stay on top of things (3 Year), see value labels	parent	item	integer	ordinal	1=untrue, 2, 3, 4, 5=true
cyhtv	Home chaos item 5: television usually on (3 Year), see value labels	parent	item	integer	ordinal	1=untrue, 2, 3, 4, 5=true
cyhzoo	Home chaos item 3: its a real zoo (3 Year), see value labels	parent	item	integer	ordinal	1=untrue, 2, 3, 4, 5=true
czyblood	Twin blood groups known (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
czyears	Differences in ear lobes (3 Year), see value labels	parent	item	integer	ordinal	1=no difference, 2=only slight difference, 3=clear difference
czyeyes	Differences in eye colour (3 Year), see value labels	parent	item	integer	ordinal	1=no difference, 2=only slight difference, 3=clear difference
czyfac	Twins have different blood rhesus factors (3 Year), 1Y 0N	parent	item	integer	nominal	0=no (same), 1=yes (different)
czygrow	Likeness changed as twins grown older (3 Year), see value labels	parent	item	integer	nominal	1=remainded the same, 2=become less similar, 3=become more similar
czyhairs	Differences in hair shade (3 Year), see value labels	parent	item	integer	ordinal	1=no difference, 2=only slight difference, 3=clear difference
czyhairt	Differences in hair texture (3 Year), see value labels	parent	item	integer	ordinal	1=no difference, 2=only slight difference, 3=clear difference
czymistb	Mistake twins for each other: babysitter/carer (3 Year), see value labels	parent	item	integer	ordinal	1=yes often, 2=yes sometimes, 3=rarely or never
czymistc	Mistake twins for each other: parents casual friends (3 Year), see value labels	parent	item	integer	ordinal	1=yes often, 2=yes sometimes, 3=rarely or never
czymistf	Mistake twins for each other: parents close friends (3 Year), see value labels	parent	item	integer	ordinal	1=yes often, 2=yes sometimes, 3=rarely or never
czymistm	Mistake twins for each other: people meeting first time (3 Year), see value labels	parent	item	integer	ordinal	1=yes often, 2=yes sometimes, 3=rarely or never
czymistp	Mistake twins for each other: other parent (3 Year), see value labels	parent	item	integer	ordinal	1=yes often, 2=yes sometimes, 3=rarely or never
czymistr	Mistake twins for each other: other relatives (3 Year), see value labels	parent	item	integer	ordinal	1=yes often, 2=yes sometimes, 3=rarely or never
czymists	Mistake twins for each other: older siblings (3 Year), see value labels	parent	item	integer	ordinal	1=yes often, 2=yes sometimes, 3=rarely or never
czyold	Recoded likeness changed as twins grown older (3 Year), see value labels	parent	item	integer	ordinal	1=become more similar, 2=remained the same, 3=become less similar
czypeas	Respondent opinion of twin likeness (3 Year), see value labels	parent	item	integer	ordinal	1=alike as two peas in a pod, 2=as alike as brothers and sisters, 3=not much alike
czyphot2	Recoded tell twins apart in photos (3 Year), see value labels	parent	item	integer	ordinal	1=no often confuse them, 2=yes but sometimes hard, 3=yes easily tell them apart
czyphoto	Tell twins apart in photos (3 Year), see value labels	parent	item	integer	nominal	0=no often confuse them, 1=yes easily tell them apart, 2=yes but sometimes hard
czyphysi	Physical differences not visible (3 Year), 1Y 0N	parent	item	integer	nominal	0=no, 1=yes
czyprobs	Differences because of birth problems/accident/illness (3 Year), see value labels	parent	item	integer	nominal	0=no, 1=yes, 2=don't know, 3=there are no differences
czyprof	Zygosity told by health professional (3 Year), 1MZ 2DZ	parent	item	integer	nominal	1=MZ, 2=DZ
czyteet2	Recoded differences in teeth coming through (3 Year), see value labels	parent	item	integer	ordinal	1=matching teeth within a few days, 2=not matching or not within a few days
czyteeth	Differences in teeth coming through (3 Year), see value labels	parent	item	integer	nominal	1=matching teeth on same side within a few days, 2=matching teeth on opposite sides within a few days, 3=different teeth within a few days, 4=not within a few days of each other
czytoget	Twins mistaken when together (3 Year), see value labels	parent	item	integer	ordinal	1=yes often, 2=yes sometimes, 3=no almost never, 4=not mistaken for one another
czytyp	Twins have different blood groups (3 Year), 1Y 0N	parent	item	integer	nominal	0=no (same), 1=yes (different)
czyyou	Zygosity opinion of respondent (3 Year), 1MZ 2DZ	parent	item	integer	nominal	1=MZ, 2=DZ